Thursday, October 4, 2007

Battery Discussion Follow-up: A Battery Revolution?

Thanks to everyone who attended/participated in the recent Battery Discussion ('A Battery Revolution?', Oct 3, '07). There was a ton of participation for a diverse number of people with great backgrounds/perspectives.

I've been requested to follow up the discussion with this blog to encourage continued discussion on this topic. I'll first summarize some of what we talked about, then try to stimulate more discussion.

I've uploaded a slideshow and the handout I put together for the discussion:http://mit.edu/bradwell/Public/BatteryDiscussion/

----Recap:

-Batteries are appealing because they have a low enough cost, long lifespan, are very reliable, and have enough power-to-energy suitable for most portable applications. Batteries were really enabled by portable applications - otherwise, electronic devices can simply run off of grid power, or generator power.

-Fuel cells have higher energy/power density that batteries, but their round-trip efficiency is ~35%, compared to >90% for Li-ion batteries, and they are more expensive.

-Neither batteries nor fuel cells, in of themselves, are 'renewable energy sources', but rather, they could play a role in the energy infrastructure, enabling renewable energy sources (like wind, solar, hydro, nuclear (?)) to charge the batteries/create hydrogen, which in turn, could power our cars. This could break the CO2 cycle and reduce dependence on foreign oil.

-Flywheels and capacitors can supply a lot of power, but do not have good energy density (or cost per unit energy, $/kWh).

-There is a company in Texas (EESTOR) making some pretty revolutionary claims about new ultracapacitors with higher 'energy' density that lithium-ion batteries (not to mention, longer lifespan, lower cost, and high power density). I would be very excited if this becomes a reality, but I am skeptical until I see a working model.

-There was much discussion about the use of batteries in hybrid electric vehicles (HEV's) /plug-in (PHEV's). Batteries are certainly pushing towards these markets, but they have more challenges to overcome, including safety, cost, and energy density.

-Lastly, the talk shifted towards other applications, such as renewable energy (i.e. wind power) support. Such a storage device must cost ~$100/kWh, have moderate efficiency (>70%), and very long lifespan (>3000 deep cycles). It's a very tough market to enter, but if a battery can do it, it's a 'game changer'. Some utilities in the US are already installing sodium-sulfur (NAS) or flow batteries (Premium Power) for this (and other) grid power applications. The cost of the NAS battery alone is ~$170/kWh, vs. $100/kWh for lead-acid batteries (which don't have the cycle-life required for these applications), vs. $1000/kWh for Li-ion batteries.

----

There were a couple of areas that we touched upon but didn't have any good answers to. I'd like to finish this post by posing the following questions:

1) What makes up the cost of a battery? I've heard that ~30% is materials related - but what are the other cost components? (i.e. manufacturing, transportation, labor, disposal of toxic chemicals?)

2) Is there a "Moore's Law" equivalent for batteries? How has the cost/energy density/power density improved over time?

9 comments:

I provide an excerpt from a battery report I wrote for an investor a couple of years back to provide some food for thought on the cost issue of batteries for HEV's and PHEV's:

:The production costs of currently deployed NiMH batteries in HEVs are believed to be ~$600-1200/kWh. Materials cost typically accounts for ~50% of the production costs of batteries.

Battery electrode materials used to date have tended to be expensive and in recent years, have become more expensive as commodity prices in general have risen. The hydrogen storage anode of the NiMH battery contains significant amounts of Ni and Co while the cathode consists primarily of Ni. Both Ni and Co are expensive metals and are becoming more expensive. In the mid 1990’s, Ni for NiMH cathodes batteries cost ~$7/kg, while prices have risen to ~$25/kg in recent years. The traditional Li-ion chemistry has a cathode containing significant amounts of Co (LiCoO2) as well, causing the materials cost of Li-ion batteries to be significant. (Currently, ~20% of global Co production goes into Li-ion batteries!) The development of highly performing battery electrode materials with lower cost will significantly reduce total battery cost. An example of this is the LiFePO4 cathode Li-ion batteries currently being developed by Valence Technologies and A123 Systems, which replaces expensive Co with low cost Fe, resulting in reduced battery cost.

Production-related costs typically account for ~50% of total battery production cost. The development of new battery fabrication processes and economies of scale as the HEV and PHEV markets grow is expected to lower production-related cost considerably.

Currently, OEM auto manufacturers are charging ~$2300-$3000/kWh for the NiMH HEV batteries in HEV’s, significantly more than the aforementioned estimated production costs. It can be seen that the add-on cost charged by OEMs composes up to 60-80% of the total battery cost in HEV’s that are sold. It is believed that these OEM add-on costs come down as OEM HEV manufacturer’s develop experience, confidence, and increased competition.

Furthermore, the lifetime battery cost for HEV batteries depends both on the initial battery cost in $/kWh and the battery replacement time. Accordingly, the increases in battery cycle life and calendar life discussed above will have very positive effects on the lifetime battery costs for HEV’s.

That's terrific information - thanks the info. Can you post any links to the actual report? I'd be curious to learn more details of the manufacturing processes/costs.

To address you're question: 'Round trip efficiency' is the amount of energy you get out of a storage device (i.e. battery or fuel cell), divided by the amount of energy you have to put in. For a battery, this is a pretty easy calculation based on 'electrical energy in' vs. 'electrical energy out'.

For a fuel cell (FC), it can become more complicated: For a hydrogen FC using hydrogen electrolyzed from water, the 'energy in' is the energy required to electrolyze the water to produce H2, and the 'energy out' is the electrical energy provided by the fuel cell. Although a fuel cell is much more efficient than a gasoline engine (reaching ~60% conversion of chemical energy (H2) to electrical energy, compared to ~35% for a gasoline engine), the electrolysis has a similar efficiency, resulting in a round-trip efficiency of 0.6 x 0.6 = 0.36, or 36%. Compare this to 90-95% for a Li-ion battery.

This means that in order to power a fuel cell car, you'd need 2-3 times the amount of energy compared to a battery power electric vehicle. That's like doubling-tripling the fuel economy of your vehicle - that's a big difference.

About Moore's law for batteries: I heard Martin Eberhard (confounder of Tesla motors) speaking at Stanford in October '07. In his speech he mentioned that Li Ion batteries were improving at 10% per year. I'm not sure if that was $/kwh or kwh/kg.

Peter - thanks for your comments. The link you gave didn't work that well, so I recommend people check out pg 12 of "Solid State Ionics for Batteries" and there's a plot of energy density (Wh/l) vs. time, and shows Li-ion batteries approaching 500 Wh/l.

I know Ag-Zn batteries have gotten some press about challenging Li-ion batteries in this figure of merit. Any idea of how this technology compares?

Our global dependence on fossil fuels and our urgent attempts to free ourselves from this dependence have revealed a significant deficiency in our current energy generation and supporting infrastructure. We are making great strides in the energy generation field with a nuclear renaissance on the horizon and the emergence of new and innovative ‘green’ technologies; nonetheless, these gains are offset by the inefficiencies inherent in our infrastructure. Unless we invest in and develop our capabilities to store efficiently the energy that we are producing, we are only going to add to the problem. We need a cost-effective, reliable and efficient energy storage platform to 1) transfer energy into, 2) store the energy, and 3) release it when needed. If this ideal platform existed today we would be much closer to true energy independence. The consequence of such a break-through in energy storage technology would truly change the face of the globe and help us realize our dreams.

In order to gain a better perspective on what a universally desirable energy storage device should comprise, we should look at each of the processes above. This may be an overly simplistic view of energy storage, but it does provide insight into what we are up against. Of the three processes, numbers 1) and 3) are the biggest culprits when it comes to wasting the energy we are trying to conserve. These losses are repetitive and additive and are a consequence of the inability of the energy storage device readily to accept energy and its reluctance to release it when needed. For example, if you take an ordinary lead acid battery, the amount of energy required to recharge it is always greater than what is actually stored, and you can never get as much out of it as it can store. These inherent short-comings have been accepted in the industry and design philosophies have followed suit. The industry as a whole has adopted a design philosophy that compensates for energy storage device inadequacies rather than trying to fix the problem. In other words, the industry accepts the energy storage device ‘as-is’ and then designs its systems to work around the problem. This line of thinking is wrong and it is not an acceptable approach for those interested in energy conservation. AGT has identified, and is targeting the root cause for these energy losses by attacking it at the most fundamental level.

AGT’s patent-pending technologies (protections held in the US, Canada and Europe) offer customized Ultrasonic Energy Efficiency Improvement (UEEI) solutions for all battery based applications. AGT uses high-frequency, low-level ultrasonic energy to alter the electro-chemical conversion process within the energy storage device. Specifically, the ultrasonic signal is tailored to enhance the energy storage devices internal electro-chemical diffusion characteristics. By doing so, the energy losses (waste) associated with this limiting characteristic during the transfer of energy to and from the energy storage device are significantly reduced. AGT recaptures the wasted energy and uses it for its intended function. Until now, this energy storage device characteristic was considered fixed and dependent on the chemical make-up of the energy storage device—AGT recognized that it is also dependent on the influence of ultrasonic energy. Thus, the energy storage device becomes an integral part of the solution, an active and controllable component of the system, rather than part of the problem. AGT is not settling for the energy storage device in its manufactured (as-is) form; we take a commercial product, we modify it, and we control it to fit our application.

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Benefits of AGT’s Patent-Pending Technology and Process

• The size of a battery pack can be greatly reduced, to 1/3 of 1/2 of its original size • Higher peak currents are available during discharge (power), up to 3X greater • Faster charge times to 100% State of Charge (SoC), as much as 5X faster • It will last 5-10 times longer, sharply reducing the need for battery pack replacement • Its charge acceptance at lower currents is significantly increased (Solar)• Its internal impedance can be adjusted to compensate for less than ideal wind speeds (Wind)• The level of control is limitless and it is real-time, thereby allowing for compensation for load changes, environmental changes, etc• The level of control can be altered via customized software solutions: A programmable battery pack• Less weight compliments the plug-in hybrid initiative (40 miles on single charge)• Lowered impact on the environment, fewer batteries being discarded• Less gassing and at lower charging potentials, less sensitive to the cold (Fork-Lift)• Industrial and residential applications• Truly revolutionize energy storage without disrupting current production and distribution channels• Cost effective and scalable solutions for energy storage worldwide

If we truly want to minimize or eliminate our dependence on fossil fuels and move toward a ‘green’ environment, we are going to have to change the way we think about energy storage. AGT has dedicated itself to solving these problems and will pave the way for others to follow. The gains achievable with the application of AGT technology are boundless.

I admire the inspiration for newer innovations. IF vehicles were operated by lithium ion batteries then the world would literally be a different place. ME myself mainly caring for the environment itself would really hope for the best case scenario and would wish that vehicles would run on them batteries!IF it were possible though, many corporations would lose a lot of money..Look guys, there are plenty of different alternatives for the car running on a different energy source. Cars today have the ability to run on propane, vegetable oil, water, and battery, but if these acts were to be in effect asap, big companies would lose business thus luxurious companies not being able to pay off many things in essense declaring bankruptcy. It will disturb the whole economic status of car dealerships because competition would compare to cellular phone business. A shop in every corner and not a need for it as much..Dell notebook batteries